Profitability in dairy operations is directly related to reproductive performance. The results of the preferred reproductive program in the dairy farm will be used to measure essential parameters of success, for instance, decreasing replacements due to reproductive failure and increasing the number of heifers for replacement due to reproductive success.
These examples are directly connected to dairy revenue and must be considered before making any reproductive management decision. Many different reproductive strategies are available for dairy managers. However, the complexity of these choices interacting with biological and economical factors can make the best management decision a difficult challenge.
The undeniable success of hormonal protocols
In spite of the undeniable success of the use of hormonal protocols to synchronize ovulation in the dairy industry since the early 1990s, the first timed artificial insemination (TAI) protocol, termed Ovsynch, increased the insemination risk but not the fertility of dairy cows. However, in recent years, new protocols such as Presynch-Ovsynch or Double-Ovsynch were developed to increase both the insemination risk and the fertility of TAI programs. Lately, these protocols have been improved, with modifications such as giving an extra prostaglandin (PG) injection on day eight of the protocol in order to improve luteolysis and the subsequent ovulation.
Accordingly, many dairy farmers in the Midwest have decided to perform 100 percent TAI without estrus detection (ED), deciding to not take any advantage of the traditional heat detection. On the other hand, many Western and Southwestern producers with relatively efficient ED programs still resist the idea of implementing any TAI protocols in their herds, deciding to ignore any benefit the synchronization protocols could bring to their dairies. They still breed 100 percent of the cows after ED, probably due to labor constraints and hormone costs. There will be advantages and disadvantages in either case, but we should be able to take advantage of both programs and consider that combining TAI and ED could benefit the modern dairy operation.
Finding the perfect combination: TAI and ED
The combination of TAI and ED has been used by the majority of dairy farms in the U.S. Basically, the dairyman uses the TAI program, starting with the pre-synchronization injections. However, only those cows not detected in heat during the protocol are bred by TAI. This allows some flexibility in the timing and type of injections. For example, the commonly used Presynch-Ovsynch protocol, which consists of a pre-synchronization with two PG injections 14 days apart and 10 to 14 days later followed by the Ovsynch as a TAI program (D0 GnRH, D7 PG [a second PG could be given here on D8 to improve luteolysis], D9 GnRH, and D10 TAI). The two main advantages of this program are: a) the cows showing heat after the second PG injection of the pre-synchronization can be bred, reducing the number of cows that will complete the program, decreasing hormone costs, and b) the cows that did not show heat will probably be in a better stage of the estrous cycle (between days five and nine) to reach higher fertility in the TAI program.
Other implicit advantages of using the combination of TAI and ED can be verified in both larger and smaller herds. In larger herds, if we rely only on ED by using tail chalking with an additional secondary sign of estrus – such as a red swollen vulva, ride marks, vaginal mucus or a normal 18 to 24 days estrous interval – we know that periodic evaluations and retraining of technicians will be required. If these steps are absent, poor results may occur. On the other hand, in smaller herds, only visual methods are used to detect heat, but in the U.S., the sizes of the herds are trending upward, increasing by 142 percent over the last 20 years (from 74 to 179 cows). Traditional methods of visual ED do not work well when cows are managed in larger groups, simply because there are more cows, which means less accuracy and more time required for ED, identification, sorting, breeding and record keeping.
Consider the cost
These factors aside, we still must determine the importance of the use of ED combined with TAI to the dairy farm’s bottom line. To answer this question in a more precise way, many simulation models have been used to predict the impact of a wide range of reproductive management scenarios and performance levels. One model was developed by the University of Wisconsin – Madison and Cornell University. The UWCU-DairyRepro$Plus predicts the future profitability of a dairy, comparing different reproductive management programs. (Available for free download on the UW-Madison Department of Dairy Science website.)
This specific model was used by Giordano et al. to compare the profitability (net value) of 19 different programs, including one that used 100 percent TAI (42 percent conception rate for first TAI), while the others combined ED with TAI programs in the proportion ranging from 30 to 80 percent, with conception rates (CR) of 25, 30 and 35 percent. As the proportion of cows receiving A.I. after ED increased, the CR of cows receiving TAI decreased. When compared with the program relying 100 percent on TAI, programs reaching 25 percent CR to the ED had a lower net value at all levels of ED.
On the other hand, combined programs reaching 30 percent CR with the proportion up to 60 percent of cows receiving A.I. after ED had greater net value than the program that used only TAI. Also, the combined program with a CR of 35 percent for cows receiving A.I. after ED had the greatest net value and reproductive performance at all levels of ED.
In summary, the reproductive management decision to make a dairy herd more profitable when combining TAI and ED depends on the proportion of cows receiving A.I. after ED and also on the level of conception rate. In other words, submitting the whole herd solely on TAI, ignoring ED and retraining breeders on heat detection, or on the other hand, breeding exclusively after ED, closing your eyes to the excellence of the new synchronization protocols, may not compound the most profitable reproductive management program for your dairy herd. PD
- Technical Service Consultant
- ABS Global
- Email Anibal Ballarotti